Preparation and microwave absorbing properties in the X-band of natural ferrites from iron sands by high energy milling

Bulk natural ferrites based in iron sands were synthesized at room temperature by high energy ball milling. The reduced particle sizes of the ferrites were milled at 100 rpm at selected time intervals of 0, 2, 4, and 6 h. The as-milled products were then characterized by x-ray diffraction (XRD), a vibrating sample magnetometer (VSM) and a vector network analyzer (VNA). The results showed that the magnetite phase contents, their mean size and the saturated magnetization of the natural ferrites were about 95 nm and 36-.50 emu g^-1 without a new phase. The microwave absorbing characteristics were investigated by measuring the absorption of electromagnetic waves in the frequency range 7-12 GHz. The maximum reflection loss (RL _m) and matching frequency (f _m) for the best process of milling (100 rpm, 6 h) of natural ferrites were RL _m1= -7.28 dB in f _m1= 7.50 GHz (▵f= 1.50 GHz) and RL _m2= -4.31 dB in f _m2=10.28 GHz (▵f= 2.57 GHz). These results suggest that synthesized natural ferrites can be employed as effective microwave absorbers in various devices.